Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: Sara2020 on July 23, 2020, 10:34:07 AM

Title: Crate G130C Amp
Post by: Sara2020 on July 23, 2020, 10:34:07 AM
 Hi Everyone, I have a Crate G130C Amp that I bought new in in the mid 90's. At some point I started having an issue with the Amp where the output sound would fade out. If it would cool down, it would temporarily start working again. I sent the Amp in to SLM Electronics / Crate, in St Louis, Missouri and they fixed the issue. It worked fine for many years but has developed the same problem again. As you probably know, they have went out of business. I took the circuit board out of the Amp and have replaced a few resistors that had split open from overheating,but that didn't fix the main problem. I recently found the paperwork that SLM Electronics sent me when they repaired the Amp before. It says that they had replaced a "Leaky Zener Diode for the low voltage power supply"  They unfortunately didn't put a part number for the Zener Diode on the invoice. I have ran across the schematics for this Amp but I can't tell where the Zener Diode is for the low voltage power supply. Could someone please help direct me to where the Zener Diode is located on the circuit board?
Title: Re: Crate G130C Amp
Post by: Jazz P Bass on July 23, 2020, 11:51:25 AM
Piease post the relevant schematic.
You really should test the power supply before assuming the failure mode is the exact same.
Title: Re: Crate G130C Amp
Post by: Enzo on July 23, 2020, 01:26:58 PM
And the factory doesn't need to be there, ANY competent amp tech can repair this.  I bet you have a local shop.

I surely wouldn't assume the same zener needs replacement.  It MIGHT of course, but frankly it is more likely your FX loop jacks have dirty contacts.
Title: Re: Crate G130C Amp
Post by: g1 on July 23, 2020, 02:20:44 PM
schematics/service manual attached.
Title: Re: Crate G130C Amp
Post by: Jazz P Bass on July 24, 2020, 12:51:35 AM
To answer the posts question, here is a crop of the power amp board locating D16 (+16Vdc) and D17 (-16Vdc)
Title: Re: Crate G130C Amp
Post by: phatt on July 24, 2020, 02:14:45 AM

Quote;
* At some point I started having an issue with the Amp where the output sound would fade out.*
Then,,
Have you checked your FX loop? a common cause of intermittent signal drop out.
Phil.
Title: Re: Crate G130C Amp
Post by: Sara2020 on August 07, 2020, 08:31:16 PM
I've checked with a couple of local electronics repair places and they want more to look at the Amp than the Amp is worth. I've recently purchased a Blackstar HT Stage 60 for myself and was hoping to get the Crate fixed, as inexpensive as possible for my teenage son to use with his guitar. Thanks for the comments so far. I'm taking your suggestions into consideration.
Title: Re: Crate G130C Amp
Post by: joecool85 on August 07, 2020, 08:54:55 PM
Quote from: phatt on July 24, 2020, 02:14:45 AM

Quote;
* At some point I started having an issue with the Amp where the output sound would fade out.*
Then,,
Have you checked your FX loop? a common cause of intermittent signal drop out.
Phil.

Phil is on it.  Try running a patch cable between the FX send and return jacks.  If this fixes it, your jacks just need to be cleaned (or replaced if it really bad shape).